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3 hours ago, BWM said:

Are all DM2 engines 14hp/max 800rpm, or do they vary with age like Jp's? My son has just bought a boat with a 1940 unit, I have been helping to move it from Suffolk to Rickmansworth for the last week (scuppered by badly advertised stoppages on the Nene). An enjoyable engine but I couldn't help thinking a little more oomph at the top end would have been useful. 

The numbers I would come up with for the normal narrow boat engine are 18HP and 1,200 max RPM.

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54 minutes ago, captain birdseye said:

I was always told 15HP at 1000RPM, but 'modern' ones are rated 18HP at 1200RPM

 

17 minutes ago, alan_fincher said:

The numbers I would come up with for the normal narrow boat engine are 18HP and 1,200 max RPM.

There is a brass plate on the engine stating max rpm and horsepower, I'm guessing that is down to the age of it.

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5 hours ago, alan_fincher said:

The numbers I would come up with for the normal narrow boat engine are 18HP and 1,200 max RPM.

 

4 hours ago, BWM said:

 

There is a brass plate on the engine stating max rpm and horsepower, I'm guessing that is down to the age of it.

 

Original 1930s documentation talks about 18/20 HP (whatever that means).

 

Looking at a photo of  a much later 1987 Dagenham built unit that was in a boat we were trying to buy, it clearly shows 18HP and 1,200 RPM.

Personally I can't recall coming across lower rated ones, but I'm not doubting they exist.

Were they all marine engines though?  I'm well aware that with Listers an industrial version may well be rated less, and at a lower max RPM, than a marine engine.

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32 minutes ago, alan_fincher said:

 

 

Original 1930s documentation talks about 18/20 HP (whatever that means).

 

Looking at a photo of  a much later 1987 Dagenham built unit that was in a boat we were trying to buy, it clearly shows 18HP and 1,200 RPM.

Personally I can't recall coming across lower rated ones, but I'm not doubting they exist.

Were they all marine engines though?  I'm well aware that with Listers an industrial version may well be rated less, and at a lower max RPM, than a marine engine.

 

Not sure about old diesels, but modern ones used for generator applications have two ratings for the same engine, dependent upon use..  

 

1. Continuous - generator can run at 100% electrical rated load (kWe) continuously, with q hour in 12  at 110% electriCal load.

 

2. Sprint or Fuel Stop - generator can run at (typically) 125% electrical rating (kWe) provided total running time is not more than 250 hours per year.

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2 hours ago, alan_fincher said:

 

 

Original 1930s documentation talks about 18/20 HP (whatever that means).

 

Looking at a photo of  a much later 1987 Dagenham built unit that was in a boat we were trying to buy, it clearly shows 18HP and 1,200 RPM.

Personally I can't recall coming across lower rated ones, but I'm not doubting they exist.

Were they all marine engines though?  I'm well aware that with Listers an industrial version may well be rated less, and at a lower max RPM, than a marine engine.

 I don't know enough about them to identify one type from another, but the fact that it has a mechanical gearbox and otherwise resembles other marine versions of the period leads me to assume that it is. I'll take a picture of the plate next time I visit the boat. 

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Just awoken to see this thread subject and being a DM3 owner for 12 years or so, will add my feedback.

 

I understood from talking to several owners and Dave Bixter that DM engines were rated at 22hp for a DM2 and 33hp for a DM3.

 

I would suggest that these are understated and real world numbers unlike some more modern, higher revving items,,

 

Performance depends on boat style, weight (only just) and water conditions,  my boat moves well at low revs,,  eg @ 100 pm. but can also blast along at @ 1200 if required..at the top end she does indeed perform well, likewise fuel use also reflects use,,  gearbox type/prop size etc etc

 

I have  had to replace a few parts and  strip the engine..  in some senses parts are indeed expensive, but if rated over say 30 years among running costs then she has not been expensive to run at all.  All parts have been available of the shelf!  from RN, 

I wouldn't say cheap but rather good value,  I've known some others replace parts 2 or 3 times with other makes,,,the associated costs being some what more overall than  mine, but also recognise that you are buying an 80 year old working item,,,steady checking and maintenance is key

 

sound wise a dm3 is softer and rather pleasant on the ears,,,

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On 05/11/2018 at 18:13, alan_fincher said:

 

 

Original 1930s documentation talks about 18/20 HP (whatever that means).

 

Looking at a photo of  a much later 1987 Dagenham built unit that was in a boat we were trying to buy, it clearly shows 18HP and 1,200 RPM.

Personally I can't recall coming across lower rated ones, but I'm not doubting they exist.

Were they all marine engines though?  I'm well aware that with Listers an industrial version may well be rated less, and at a lower max RPM, than a marine engine.

 

On 05/11/2018 at 21:16, captain birdseye said:

If it is labelled DM2 it is a marine, the static engine was labelled D2

This is the plate I mentioned, along with a picture of the engine. I can't see either D2 or DM2 on the plate though. 

20181110_151856.jpg

20181110_152130.jpg

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15 minutes ago, BWM said:

 

This is the plate I mentioned, along with a picture of the engine. I can't see either D2 or DM2 on the plate though. 

 


I can't put my finger on exactly what but it certainly has differences to some RNs I've seen in narrow boats.

Looking a photo of a known later DM2 data plate, (Dagenham made engine), it doesn't identify the engine type either.

Is the owner a member of the "RN Register"?  What do they say about the engine, if you provide them with the serial number?

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Looks like a D2 to me. 

 

seems to be too old to be mated to a prm gearbox ie its a marinised industrial unit probably ex generator.

 

Exhaust manifold looks wrong.

 

IMO 

 

Eta interesting to see recommended fuel is Diesoline. I have not come across that before. 

 

Quick Google suggests this is a 15% v/v gasoline:diesel mix. 

 

Gasoline being 4 star petrol I guess. 

 

I wonder if this was an export unit which found its way back to england. 

Edited by magnetman

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13 hours ago, alan_fincher said:


I can't put my finger on exactly what but it certainly has differences to some RNs I've seen in narrow boats.

Looking a photo of a known later DM2 data plate, (Dagenham made engine), it doesn't identify the engine type either.

Is the owner a member of the "RN Register"?  What do they say about the engine, if you provide them with the serial number?

The engine is in a boat my son has just bought, and I know next to nothing about it. I will try to contact the RN register, thanks. 

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Well, the engine is a Altrincham build which dates it pre 1949, which is when the Altrincham works closed. Looking through old RN Register newsletters (i'm sure there is a list of engine numbers with details somewhere in one) there is an article about a D2 number 3553 which was built to run a welding set which was made by Metro Vic's in the late thirties. The owner thinks it was an original installation so the above engine would have been of a similar vintage and possibly for a similar purpose. For the OPs information the article is in the Winter 2014 Issue 84 Newsletter

Edited by captain birdseye
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On 10/11/2018 at 18:42, BWM said:

 

This is the plate I mentioned, along with a picture of the engine. I can't see either D2 or DM2 on the plate though. 

20181110_151856.jpg

20181110_152130.jpg

No hand start mechanism, and not hugely different but the air filter is on the opposite end of the DM2 I've been entrusted to play with recently.

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in my usage of a national at a good old age, the only really problems I've really had have all been down to aged pipes that have worn thin.

 

mine use to leak oil like no end but this was solved by simply changing the oil pipes externaly. I also had probs with fuel pipes.

 

In my honest op the engine is fairly fuel efficient 25-30L in 5 days of solid long boating. power wise with the right prop I can't say I don't have enough I can stop and go very well, my limit would be me not pushing it or depth.

 

cost wise I can't say it's had or not for a vintage engine ive spent far less on my national than a fr2 engines but sometimes you get a goodun others a bad one.

 

I love the sound and yes it's big but that's also the gearbox too. it's not what i would have bought but i wouldn't put my nose up at a dm2 a 3 I would never use enough along with most older 3 cylinders. unless you do rivers a fair bit or have a tug that you actually use as a tug. just my 2p

On 11/11/2018 at 19:40, Liam said:

No hand start mechanism, and not hugely different but the air filter is on the opposite end of the DM2 I've been entrusted to play with recently.

14hp seams low???? or is that just me?? given the national is same engine giving 18hp

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Because the torque curve on a diesel is pretty flat, power out put is usually proportional to speed, within mechanical limits .  So the plate pictured is for a 14 hp engine at 800rpm.  That is the same as 18 hp at 1000 rpm once the governor has been adjusted to allow for the higher speed. If you run it up to 1200 rpm then you will get ~22 hp. I doubt there were any changes to allow the greater ratings, except to the governor settings.

More speed equals more power is  not limitless because either something will break or the engine will not be able to get enough air in or the fuel pump won't keep up, but for small changes it is OK.

N

 

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